Need direction - Bosch Singular 5200

Robbi

Hi! I've been reading this forum for many, many months now - educating myself from scratch and it has been super helpful. It's now time for me to post -

Firstly, thank you to all those that have responded to other's posts for help and for providing outstanding information. You are heros and I hope you know that.

My setup -

I installed a Bosch combi Singular 5200 for my 3100sqft home here on Long Island. I had a cast iron boiler prior, but ditched it after 35 years for certain issues. I repiped everything with 3/4in Pex C (oxygen barrier) and kept the original Slant fin 2000 (25+ years old), but replaced some of it. I wanted 1 giant zone (loop) for the whole house. This was done purposely. One thermostat. I have one external pump pushing the whole system. I have 92 feet of slant fin for an almost 70 year old home (terrible windows in most of house). I'm slowly renovating room by room and adding insulation.

My Dhw is awesome and has shown no issues. I'm preparing for the winter because last winter things didn't go well. Often, I had to utilize my heat pump in parallel (Bosch 2.0 at 3 tons for majority of the home). Ranch style home. I only want to use the boiler during the winter, but it could not keep up at all with the house. Heating bill/electric bill was insanity as a result.

1.How much did I screw myself with oversizing the boiler?

2. If I add more slant fin, will that help heat up this house and get my unit to condense properly?

3. Could there be air in the line holding the baseboards back from properly heating? I bled as much as I could (saddle valves), but I can't bleed all of them since they don't have bleeders. If I recall correctly, around 90-95 degrees F coming out.

What are your thoughts - be brutal if need be, so I can correct before the winter months settle in. Some days are 17-20 degrees Fahrenheit during the winter.

Set temp on boiler is 180 and 120 for dhw. The unit will be 1 years old this December 25th.

Thank you in advance - will check this regularly to provide responses. Will keep updated as I implement suggestions (for those that might have similar issues). Please and thank you!

With great regard,

Rob

Big Ed_4

Around 65' of baseboard you can run on each loop …. 92' is too much on a series system …You can parallel your system in half with 1" supply and return … Add purge valves to remove air on each loop…

Panel radiators and the outdoor sensor works well with your boiler …

Robbi

Hi. Thanks for the response. Why is 90+ feet problematic?

Does it help if there are actually 3 sections that meet into one and go back as the return (same for the supply)?

There are valves for each of these small sections, but they're lower than the baseboards - they're meant to drain the loops. My secondary loop (close tees) is currently 1in Pex. Thank you!

Jamie Hall

The key question on the 90 feet. And I'm not clear on the piping. Does the water flow from the boiler to one section of 30 feet. them on to the next one, then on to the last one, and then back to the boiler? Or does the water flow from the boiler individually to the beginning of each 30 foot section, then return individually to the boiler? The first arrangement is called "serial" piping, and the second "parallel".

Now if it's serial piping, what happens is that the water temperature drops as it goes through each section, as the heat is given off by the radiator. So the first section gets nice hot water, the next one sort of medium, and by the time the water has made it to the last section in line it's actually pretty cool. And that last section just won't heat.

Robbi

https://forum.heatinghelp.com/discussion/comment/1809284#Comment_1809284

Hi. The 3/4 Pex C travels from the supply heating, hits the first baseboard and then travels to a tee where it goes to one section of the house, where it then tee's off to the other two sections of the home. And then the 3 sections meet at the return line back to the boiler. Could you maybe say that it's a hybrid of both serial and parallel? Thank you!

Jamie Hall

"Hybrid" would be a kind word. Is there any way you can rearrange the piping so that each section is fed individually from a manifold of some kind — doesn't have to be right at the boiler — and each returns individually to another manifold, and then the whole lot returns to the boiler together?

Robbi

https://forum.heatinghelp.com/discussion/comment/1809289#Comment_1809289

Hi. I can do anything - may I trouble you for an example illustration or product you might suggest, please? Thank you kindly

Robbi

https://forum.heatinghelp.com/discussion/comment/1809297#Comment_1809297

After briefly researching online, there doesn't seem to be any product for my need. I'll likely rearrange using a couple of tees and an elbow, but would this be all that different from what I have now? Would flow be impacted?

Big Ed_4

The supply to your parallel system is too restricted , 1" ID minimum on two 3/4"loops 1 1/4" ID on three .75" loops , The better flow will , also help you later when balancing .. What you have for a supply is too small , crimped Pex system is not helping ..

Robbi

https://forum.heatinghelp.com/discussion/comment/1809351#Comment_1809351

Hi. Are you proposing I change my 1in Pex secondary loop (close fitted tees) to 1-1/4in pex? Or are you suggesting I ditch the 3/4in pex lines for 1-1/4in Pex?

Big Ed_4

Three loops , you run a 1 1/4" from the boiler to a point where all the loops meet , connect the returns to a single 1 1/4" pipe then return to boiler .. You would need ball valves on each loop and a purge valve set up ….

Robbi

https://forum.heatinghelp.com/discussion/comment/1809358#Comment_1809358

I'm on it - will do within next few weeks. Will touch base then - thank you!

Big Ed_4

Ask First …it's easier …..

Robbi

Your previous comments were more than enough - thank you

Big Ed_4

Three speed circular would be nice later when fine tuning …..

Robbi

Hi. Hope all has been well! I'm getting ready to gear up to make the necessary changes.

What is a three speed circular? That a variable speed external circulation pump?

Any suggested units? Always partial to taco 007e